1. Field of the Invention
The present invention relates to an ultraviolet ray measuring apparatus and an electronic wristwatch equipped with an ultraviolet ray measuring function.
2. Background Art
In the past, electronic devices equipped with an ultraviolet ray measuring function were known that included an ultraviolet ray sensor and measured ultraviolet intensity and displayed measurement results (for example, refer to JP-UM-A-6-51837, JP-UM-A-2-60828, and JP-UM-A-2-16031). In addition, in electronic devices that measure the amount of ultraviolet rays, it is common that measurement is started by pressing a start switch that gives a command for the measurement of ultraviolet rays.
In addition, as electronic devices equipped with an ultraviolet ray measuring function in the related art, electronic devices are known that are configured to display instantaneous values when measuring ultraviolet intensity, or cumulative values of ultraviolet intensity measured (for example, refer to JP-A-2001-255205 and JP-1-262426), or average values of ultraviolet intensity measured (for example, refer to JP-UM-A-6-51837). In addition, with regard to the suppression of current consumed, technologies are known that “set the ultraviolet intensity measuring time to a specific time” (for example, refer to JP-UM-A-2-16031).
Ultraviolet ray sensors output the maximum value when facing the sun, and therefore, if not facing the sun, the intensity of ultraviolet rays cannot be measured accurately. However, in a case in which an ultraviolet ray measuring function is provided in devices that are worn on the body, such as a pedometer, a wristwatch or the like, hanging from the neck, or in small-sized mobile ultraviolet ray measuring devices in the related art, the direction of the devices is not fixed and therefore the direction of the ultraviolet ray sensor varies with each use. As a result, there are cases in which the ultraviolet ray receiving surface of the ultraviolet ray sensor does not face the sun, and thus there is a problem in that it is difficult to accurately measure ultraviolet intensity. For example, in a case in which the ultraviolet ray receiving surface of the ultraviolet ray sensor faces downward, there is a problem in that, although the actual amount of ultraviolet rays from the sun is high, the sensor determines that the amount of ultraviolet rays is low or there are no ultraviolet rays.